Coating process



- Patented July 4, 1944 COATING PROCESS I William Whitehead, Rye, N; 1.,assignor to' Celaneoe Corporation of America, a corpora- M tion. ofDelaware No Drawing. Application August 9, 1941, g v Serial No. 406.181

dClalms.

This invention relates to the treatment of textile fabrics to formair-impervious coating thereon. and relates more particularly to thecoating of textile fabrics having a basis of yarns of continuousfilaments, which are employed to cover airplane surfaces. v I

An object of my invention is the application of an impervious andweather-proof coating having a basis of a cellulose derivative totextile fabrics having a basis of yarns of continuous filaments andemployed for covering airplane wing, fuselage and control surfaces.

Another object of my invention is the application of an impervious andweather-proof coating to cellulose derivative textile fabrics, whichcoat- 7 ing will be permanently adherent to the fabric.

Other objects of my invention will appear from I the following detaileddescription.

In. the construction many types of airplanes wherein the wing load islight. cloth is extensively employed for covering wing, fusela e. tail.

and other surfaces of the airplane. To be satis factory such cloth mustpossess great strength. Generally, such cloth is woven in a tightcompact weave from yarns of high tenacity so as to form a fabric capableof resisting the various stresses and strains placed upon it. In orderto weather-proof the fabrics and also to cause them to be stretchedtightly over the frame or structure of the airplane after they areattached thereto. the fabrics are usually coated with a coatingcomposition comprisin solutions o a cellulose derivative in a suitablesolvent. The effect of this coating composition is two-fold. Upon dryingit not only forms a smooth, impervious weather-proof coating but it alsoshrinks, thus causing the fabric to which it is applied to become tautand to stretch tightly across the airplane structure. Where a fabricwoven from yarns spun of relatively short, staple fibers such as, forexample, cotton is employed, the coating becomes anchored to the fabricby means of the many individual short fiber ends projecting from thesurface of the fabric. fore the coated fabric is ready for service.however, it is essential that every projecting fiber be completelycovered by the coating composition. To this end the coated fabrics arenormally sanded down to remove any projecting fibers and the,

fabrics are then coated again. This process of sanding and recoating isrepeated until all projecting fibers are covered. In most cases. toaccomplish this, it is necessary to repeat the procedure eight to tentimes. Should any individual fibers be permitted to remain incompletelycovered and thus exposed to the'elements, the exposed fibers act aswicks and by capillary action draw moisture down into the fabric belowthe protective coating, thus overcoming the effectiveness of theweather-proof coating and seriously impairing the life of the fabric.

The above disadvantage which is inherent in the use of fabrics woven ofyarns of staple fibers may in some degree be overcome by employingfabrics. woven of continuous filament yarns. By using such fabrics,sufficient coating material may be applied to the fabric with relativelyfew coats since there are no individual fibers projecting from thesurface of the fabric and it is unnecessary to sand the coated material.The use of such fabrics,'however, has a serious drawback since thecoating material does not adhere with a satisfactory degree of strengthto the -smooth surface of the yarns or filaments comprising the fabric.This inherent lack of-cohesion between the coating material and thefabric is due to the absence of projecting fibers, and in time permitsthe coating to separate from the fabric forming blisters and peelingafter a relatively short period of service.

I have now discovered that coating compositions comprising solutions ofcellulose derivatives may be caused'to adhere tenaciously to fabricswoven of yarns having a basis of continuous filaments. In accordancewith my invention I ,treat fabrics woven of continuous filament yarnswith a material which acts as a lasticizer. for the cellulose derivativecomprising the coating composition, and the coating composition isapplied thereto. I have found that the coating composition adheres tothe structure of fabric containing the plastlcizing material to amarkedly greater. extent than when the piasticizer is absent and thatthe bond between the fabric and the coating composition is ofconsiderably increased strength and tenacity. The coating compositionmay be satisfactorily applied with,

relatively few individual coats and even after hard service the coatedfabric remains free of blisters, and peeling and cracking are whollyeliminated. 1 1

The continuous filament yarns which may be employed in the weaving offabrics to be treated in accordance with my'invention are preferablyyarns of regenerated cellulose. Such yarns may be obtained by the wetspinning of viscose solutionsin a manner well known to the art. Sultablecontinuous fllament'yams of regenerated cellulose having an unusualdegree of strength "may be obtained by the sapon 'fication of dryspun,stretched yarns having a basis of an organic derivative of cellulose.Preferably, I employ the latter due to the fact 'that they may beproduced so as to possess unusual strength and thus are highlysatisfactory for the production of fabrics which are capable of bearinga substantial degree of stress. Any suitable plasticizer or mixture ofplasticizers may be incorporated with the fabrics to produce the desiredstrong bond between the fabric and the coating composition when thelatter is applied thereto. Among the suitable plasticizers which maybeemployed are, for example, the .dirnethyl ether of ethylene glycolphthalate, dimethyl phthalate, ethyl phthalyl ethyl glycollate,triethylene glycol, triacetin, tripropionin, mono-ethyl-p-toluenesulfonamide, triphenyl phosphate, tricresyl phosphate, diethylphthalate, dimethoxy ethyl phthalate, dibutyl tartrate, camphor anddibutyl phthalate. The plasticizers may be applied to the fabrics afterthey are woven as by passing the fabric through a suitable bathcontaining the plasticizer, for example, a solution of the plasticizerin a volatile solvent therefor such as ethyl'alcohol, by padding theplastici z er or solution of plasticizer on to the fabric and thenremoving the excess by means of squeeze rolls, or the plasticizers maybe applied to the fabric in any other suitable manner. Furthermore. theplasticizer alone or in a suitable solution may be applied to the yarnsbefore weaving as by means of wicks. rollers, or other suitablefurnishing devices and the. fabric may then be woven from theplasticized yarn. Where yarns having a basis of a saponified organic derivative of cellulose are employed, the plasticizer may. if desired. beincorporated into the solutions of the organic derivative of cellulosefrom wh ch the yarns are spun, the regeneration of the cellulose bysaponification of the yarns being carried out in such a manner that theplasticizer is retained in the body of the individual filamentscomprising the yarn whereby a uniform distr bution of the plasticizer isachieved throughout the fabric. thus ensuring a. uniform bonding effectwhen the fabric is subsequently coated. I have found that excellentadhesion of t e coating composition may be obtained when from 2 to 10%of plasticizer, based on the weight of the fabric, is incorporated in orapplied to the fahric by any of the means described. Preferably.however, I employ from 3 to 5%, based on the weight of the fabric, ofplasticizer.

e coating compositions which may be applied to produce an impervious andweatherproof coatings are Well known to the art and such as thoseincorporated with the fabric may, if desired, be added-to the coatingcomposition.

Natural or synthetic resins may also .be included in the coatingcompositionto improve the strength of the resulting coating. Among thesuitable synthetic resins are those obtainable by the condensation ofphenols with aldehydes or ketones, those obtainable by the condensationof urea with aldehydes, such as formaldehyde, the condensation productsof phthalic anhydride or other dibasic acid anhydride with polyhydricalcohols such as glycerol, and many others. Natural resins such as kauricopal, manila copal and congo copal, and gums such as gum elemi are alsosuitable.

In order further to illustrate my invention, the following example isgiven:

Example I V A fabric having a warp of 100 ends per inch and a weft of100 picks per inch and comprising 60 denier continuous'fllament yarnprepared by" saponifying stretched continuous filaments having a basisof cellulose acetate is immersed in a solution consisting of 10 parts byweight of the dimethyl ether of ethylene glycol phthalate and 90 partsby weight of ethyl alcohol. The treated fabric is then subjected to acentrifuging operation. and upon evaporation of residual alcohol thereis incorporated in the fabric 4% of the plasticizer on the weight of thefabric. The fabpreferably comprise solut ons of a cellulose der vativein a suitable volatile solvent or mixture or solvents. Examples ofderivatives of cellulose whic may be employed to form the bases of thecoating compositions are organic esters of cellulose such as celluloseacetate, cellulose propionate and cellulose butyrate, mixed esters suchas cellulose acetate-propionate and cellulose acetatebutyrate. inorganicesters such as'cellulcse nirate and cellulose ethers such as ethylcellulose and benzyl cellulose.

Various volatile solvents and mixtures of volati e solvents may beemployed in "formulating the coating compositions. Suitable volatilesolvents which may be employed, depending upon the particular cellulosederivative which it is desired to dissolve. are. for example, ethylalcohol, acetone, butyl alcohol, ethyl acetate, butyl acetate, butylpropionate, ethyl lactate, diacetone alcohol, and ethylene dichloride.In order to modify the drying and other characteristics of the coatingcompositions such as flow, for example, non-solvents for the cellulosederivatives such as benzol, toluol,

xylol. solvent naphtha and benzine may be added 4 to the coatingcomposition. For increased flexibilitv in the coating upon evaporationof the volatile solvents and non-solvents, plasticizers ric is then cutand sewn to shape and attached in the form of a tightly fitting slipcover to a por-.

tion of the frame of an airplane structure. The fabric is then coatedwith a coating composition made up as follows:

' Parts by weight Nitrocellulose -Q 0.5

Ethyl acetate 3.25 Amyl acetate 1.59 Ethyl alcohol 0.134 Benzol 2.35

Example II A fabric woven of regenerated cellulose yarns as described inExample I is padded with a solution of tricresyl phosphate in acetone soas to incorporate therein 5% of tricresyl phosphate on the-weight of thefabric. This treated fabric is then cut and sewn and then placed on theframe of an airplane structure. The fa-bric'is then coated with acoating composition made up as follows:

Parts by weight Sellulose acetate Acetone 396.0 Methyl ethyl ketone 87.1Ethyl alcohol 92.0 Benzol 102.5 Benzyl alcohol 17.5 Triphenyl phosphate15.0

Several coats are appliedand permitted to .dry thoroughly betweenapplications. The coating composition shrinks the fabric and stretchesit tautly on the frame of the airplane structure. The coating adheres tothe plasticizer-containin:

fabric most tenaciously and is highly resistant to the action of theelements. The coating. remains free of blisters and is resistant tocracking and peeling. I

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein-without departing from the spirit of my invention.

Having described my invention, what I desire to secure by lettersPatentis:

1. Process for preparing a fabric having a strongly adherent coatingthereon, which comprises applying a coating composition having a basisof a. film-forming derivative of cellulose to a. fabric prepared fromcontinuous filament regenerated cellulose yarns and containing aplasticizer for the derivative of cellulose of said coating composition,selected from the group consisting of the dimethyl ether of ethylene gycol phthalate, dimethyl phthalate, ethyl phthaly l ethyl glycollate,triethylene glyco, triacetin, tripropionin, mono-ethyl-p-toluenesulfonamide,

*tartrate, camphor and dibutyl phthalate, said triphenyl phosphate,tricresyl phosphate, diethyl phthalate, dimethoxy ethyl phthalate,dibutyl tartratc, camphor and dibutyl phthalate, said coatingcomposition shrinking upon drying to cause a shrinkage of said fabric.

2. Process for preparing a fabric having a strongly adherent coatingthereon, which comprises applying a coating composition having a basisof an ester of cellulose to a fabric prepared from. continuous filamentregenerated cellulose yarns and. containing a plasticizer for the esterof cellulose of said coating composition, selected from the groupconsisting of the dimethyl ether of ethylene glycol phthalate, dimethylphthalate, ethyl phthalyl ethyl glycollate, triethylene glycol,triacetin, tripropionin, mono-ethyl -p-toluen'e sulfonamide, triphenylphosphate, tricresyl phosphate, diethyl phthalate, dimethoxy ethylphthalate, dibutyl tartrate, camphor and dibutyl phthalate, said coatingcomposition shrinking upon drying to cause a shrinkage of said fabric.

3. Process for preparing a fabric having a strongly-adherent coatingthereon, which comprises applying a coating composition having a basisof a film-forming derivative of cellulose to a. fabric prepared fromcontinuous filament re; generated cellulose yarns prepared by thesaponificati on of stretched yarns having a basis of an organic ester ofcellulose, and containing a plasti cizer for the derivative of celluloseof said coating composition, selected from the group consisting of thedimethyl ether of ethylene glycol phthalate, dimethyl phthalate. ethyl"phthalyl'.

ethyl glycollate, triethylene glycol, triacetin, tripropionin,mono-ethyl-p-toluene sulfonamide, triphenyl phosphai tricresylphosphate, diethyl phthalate, dimethoxy ethyl phthalate, dibutyl coatingcomposition shrinking upon drying to cause a shrinkage of said fabric. 1

' 4. Process for preparing a fabric having a strongly adherent coatingthereon, which cornprises applying a coating composition having a basisof an ester-of cellulose to a fabric prepared from continuous filamentregenerated cellulose yarns prepared by the saponification of stretchedyams having a basis of an organic ester of cellulose, and contaLiing aplasticizer for the ester of cellulose of said coating composition,selected from the group consisting of the dimethyl ether "of ethyleneglycol phthalate, dimethyl phthalate,

ethyl phthalyl ethyl glycolate, triethylene gylcol, triacetin,tripropionin, mono-ethyl-p-toluene sulfonamide, triphenyl phosphate,tricresyl Phosphate, diethyl phthalate, dimethoxy ethyl phthalate,dibutyl tartratc, camphcr and dibutyi phthalate, said coatingcomposition shrinking upon drying to cause a shrinkage of said fabric.

5. Process for preparing a fabric having a strongly adherent coatingthereon, which com prises applying a ,coatingcomposition having a basisof a film-forming derivative of cellulose to a fabric prepared fromcontinuous filament regenerated cellulose yarns prepared by thesaponiflcation of stretched yarns having a basis of cellulose acetate,and containing a plasticizerfor the derivative of cellulose of saidcoating composition, selected from the group consisting of the dimethylether of ethylene glycol phthalate, di-

methyl phthalate, ethyl phthalyl ethyl glycollate,

. triethylene glycol, triacetin, tripropionin, monoethyl-p-toluenesulfonamide, triphenyl phosphate, tricresyl phosphate, dlethylphthalate, dimethoxy ethyl phthalate, dibutyl tartrate, camphor anddibntyl phthalate, said coating composition shrinking upon drying tocause a shrinkage of said fabric.

6. Process for preparing a fabric having a.

strongly adherent coating thereon, which comprises applying a coatingcomposition having a basis of an ester of cellulose to a fabric preparedfrom continuous filament regenerated cellulose yarns prepared by thesaponiilcation of stretched yarns having'a basis of cellulose acetate,and containing a plasticizer for the ester of cellulose of said coatingcomposition, selected from the group consisting of the dimethyl ether ofethylene 818001 phthalate, dimethyl phthalate, ethyl phthalylethyiglycollate, triethylene glycol, tri-,

acetin, tripropionin, mono-ethyl-p-toluene sulfonamide, triphenylphosphate, tricresyl phosphate, diethyl phthalate, dimethoxy ethylphthalate, dibutyl tartrate, camphor and dibutyl phthalate, said coatingcomposition shrinking upon drying to cause a shrinkage of said fabric.

